Effective slip over superhydrophobic surfaces in thin channels

Superhydrophobic surfaces reduce drag by combining hydrophobicity and roughness to trap gas bubbles in a micro- and nanoscopic texture. Recent work has focused on specific cases, such as striped grooves or arrays of pillars, with limited theoretical guidance. Here, we consider the experimentally relevant limit of thin channels and obtain rigorous bounds on the effective slip length for any two-component (e.g. low-slip and high-slip) texture with given area fractions. Among all anisotropic textures, parallel stripes attain the largest (or smallest) possible slip in a straight, thin channel for parallel (or perpendicular) orientation with respect to the mean flow. For isotropic (e.g. chessboard or random) textures, the Hashin-Strikman conditions further constrain the effective slip. These results provide a framework for the rational design of superhydrophobic surfaces.Comment: 4+ page

Assessment of News Items Objectivity in Mass Media of Countries with Intelligence Systems: the Brexit Case

The role of mass media in society keeps the problem of manipulative influence distinction and the contiguous phenomena, chief among which is objectivity and authenticity of news items, current. The research provides a detailed study of the information broadcasting mechanisms in the media area, defines the problems, impeding an impersonal reproduction and disclosure of information, clarifies the verification methods, and gives their topology. In this research, we examined how the mass media of different countries presented the same event to the public. The publications of four mass media, concerning such an event as the withdrawal of the United Kingdom from the European Union (Brexit), have been determined as an object of the analysis. The chosen mass media refer to the countries, which are not the direct participants of that process: Russia, the USA, and Ukraine. D. Brewer’s criteria were used to define the objectivity of the news items. A relative sentiment of the news, which became the objective analysis basis, has been identified using linguistic rate with Eureka Engine intelligence system. The obtained results predominantly confirmed the hypothesis, that the mass media of different countries would represent the process of the UK withdrawal from the EU according to the country’s policy and interpret the facts in their favor. All the four mass media demonstrate the partiality when broadcasting the current situation in the matter of Brexit. The concepts being the semantic kernel elements of mass media publications have emotional coloring. The sentiment analysis of the publications resulted in the conclusion that only one of the four mass media gave a neutral assessment of the Brexit situation. The other three held to the political stance of their edition or government. The research results indicate that the problem of mass media objectivity remains relevant. The correctional impact on public opinion through mass media is extremely high. Therefore, forming the personal attitude toward the situation or event should occur with using several verifications methods and mass media sources at once

Structure of 3D Printed Ti-6Al-4V Alloy after Low-frequency Processing

The structure and residual elastic stresses in 3D printed (Selective laser melting) Ti-6A1-4V samples after the low-frequency vibration processing were investigated. The studied samples were manufactured horizontally in respect to the building platform. Different vibration oscillations modes (vertical, horizontal, and elliptical) were chosen for study. The oscillations were done with frequency of 16 Hz, and a processing time was 20 minutes. Studies shown that 3D printed samples had a high level of residual elastic stresses, which were changed after vibration treatment. The influence of the low-frequency processing on the phase composition of the alloy was found. © Published under licence by IOP Publishing Ltd

Comparative analysis of the structure and internal stress in Ti-6Al-4V alloys manufactured by 3D printing and processing with screw extrusion

Study is based on the compare characterization of the structure and evaluation of the residual internal stresses in Ti-6Al-4V samples manufactured by the 3D printing (selective laser melting) and in the Ti-6Al-4V samples obtained with using of the severe plastic deformation by screw extrusion. The microstructure and residual stresses were examined by transmission electron microscope and X-ray diffractometer. High tensile internal residual stresses in the 3D printed sample were found. The high compressive residual internal stresses were found in the hot pressed and in the twisted samples. It was shown that arising of the high residual stresses in the studied samples under various technological processes occurred in various ways. The residual stresses in the severe plastic deformed samples arose due to non-uniform volumetric plastic deformation. In 3D printed sample, the residual tensile stresses arose from both phase (martensitic) transformation and thermal deformation. © Published under licence by IOP Publishing Ltd

Direct measurements of hydrophobic slippage using double-focus fluorescence cross-correlation

We report results of direct measurements of velocity profiles in a microchannel with hydrophobic and hydrophilic walls, using a new high precision method of double-focus spacial fluorescence cross-correlation under a confocal microscope. In the vicinity of both walls the measured velocity profiles do not turn to zero by giving a plateau of constant velocity. This apparent slip is proven to be due to a Taylor dispersion, an augmented by shear diffusion of nanotracers in the direction of flow. Comparing the velocity profiles near the hydrophobic and hydrophilic walls for various conditions shows that there is a true slip length due to hydrophobicity. This length, of the order of several tens of nanometers, is independent on electrolyte concentration and shear rate

INVESTIGATION OF THE SUBJECT-SPATIAL ENVIRONMENT OF THE SCHOOL BY THE METHOD OF SEMANTIC DIFFERENTIAL

Introduction. Physical and psychological parameters of the school space have a significant impact on the motivation of a learning process and its results. Specificity of the school environment, its atmosphere and surroundings determine the meaning and nature of learning, a vector and activity of development and self-development of participants in the educational process, and determine their actions in it. This circumstance makes it necessary to develop reliable diagnostic tools that enable to study the environment of educational organizations, its impact on quality of activity and successful communications of school students and teachers. The aims of this article are the following: to reveal the possibilities of the comprehensive diagnostics of the school environment and its different spatial zones; to identify and compare the perception of school space by different participants of educational relations. Methodology and research methods. The main method of the research is Ch. Osgood’s Semantic Differential (SD) modified in the context of the features of the general stages of education. Data processing was carried out using the mid-group analysis, cross-group relations, and cluster and regression analysis using the method of step selection. Student’s t-test, Cronbach’s Alpha and Pearson’s Correlation were applied to test reliability and validity of the method of semantic differential and the received results.Results and scientific novelty. The level of suitability of a classical measurement technique by Ch. Osgood for the task solution is found out. Dichotomic pairs of characteristics of the subject-spatial environment of the school are singled out; the authors’ version of semantic differential is designed having applied those pairs. The hierarchical organization of the parameters of the subject-spatial environment of the school is proved; the level of comfort acts as the parameter integrating all its characteristics, which, however, is unequally regarded by students and teachers (total number of respondents sample was N = 661). Significant differences in the estimates of the subject-spatial environment in the groups of students and teachers (from p < 0.05 to p < 0.000) are established and described. Regression formulas for each group of participants of educational process are proposed; which can be followed to estimate optimum values of comfortable learning and professional-pedagogical activity as well as to adjust subject space of a certain school. Practical significance. The developed and approved diagnostic tool makes it possible to attract external and internal experts; to obtain the quantitative data that expand the field of application of mathematical statistics; and also can become a basis of the organization of longitudinal and comparative studies of the subject space of school. Regular monitoring can be considered as a predictor of psychological well-being conditions of an educational institution since the timely and exact estimates provide adoption of operational and effective measures for improvement of the environment of the educational organization in order to strengthen the efficiency of its performance and get better results of educational activity.Введение. Физические и психологические параметры образовательного пространства оказывают существенное влияние на мотивацию процесса познания и его результаты. Специфика школьной среды, ее атмосфера и антураж во многом определяют смысл и характер обучения, вектор и активность развития и саморазвития его субъектов, детерминируют их поведение. Данное обстоятельство обусловливает необходимость создания надежного инструментария для изучения среды образовательных организаций и ее воздействия на качество деятельности и успешность коммуникаций школьников и педагогов. Цели статьи состоят в раскрытии возможностей комплексной диагностики предметной школьной среды в целом и ее частных зон; в выявлении и сравнении оценок школьного пространства, которые даются разными участниками образовательных отношений. Методы и методики. Основным методом изложенного в публикации исследования является «Семантический дифференциал» Ч. Осгуда, модифицированный с учетом особенностей общей ступени образования. Данные опросов учащихся и педагогов обрабатывались посредством методов среднегруппового анализа, межгрупповых связей, кластерного и регрессионного анализа с привлечением методики шагового отбора переменных. Для проверки надежности и валидности метода семантического дифференциала и полученных результатов применялись Т-критерий Стьюдента, коэффициент альфа Кронбаха и коэффициент корреляции Пирсона. Результаты исследования и научная новизна. В ходе пилотного этапа исследования выяснена степень пригодности классического варианта метода Ч. Осгуда для решения поставленных задач. Выделены дихотомические пары характеристик школьной предметно-пространственной среды, из которых сконструирована авторская версия семантического дифференциала. Обоснована иерархическая система параметров предметного пространства школы, где параметром, интегрирующим все его характеристики, выступает «комфортность», которая, однако, неодинаково расценивается обучающимися и педагогами (общая численность выборки респондентов составила N = 661). Установлена и описана значимость различий (от p < 0,05 до p < 0,000) в их понимании реального и идеального предметного образовательного пространства. Предложены регрессионные формулы для каждой группы субъектов образовательного процесса, следуя которым можно определить оптимальные значения комфортного обучения и профессионально-педагогической деятельности и скорректировать предметное пространство конкретной школы. Практическая значимость. Разработанный и апробированный диагностический инструмент, позволяющий привлекать внешних и внутренних экспертов и получать количественные данные, расширяющие поле применения математической статистики, может стать основой организации лонгитюдных и сопоставительных исследований предметного пространства школы. Регулярное проведение подобного мониторинга может рассматриваться как предиктор психологического благополучия образовательного учреждения, так как своевременный и точный прогноз обеспечивает принятие оперативных и действенных мер по улучшению среды образовательной организации с целью усиления эффективности ее функционирования и повышения результатов образовательной деятельности

Optical echo in photonic crystals

The dynamics of photonic wavepacket in the effective oscillator potential is studied. The oscillator potential is constructed on a base of one dimensional photonic crystal with a period of unit cell adiabatically varied in space. The structure has a locally equidistant discrete spectrum. This leads to an echo effect, i.e. the periodical reconstruction of the packet shape. The effect can be observed in a nonlinear response of the system. Numerical estimations for porous-silicon based structures are presented for femtosecond Ti:Sapphire laser pump.Comment: 4 page

Russian and Foreign Experience of Placement for Orphans

Children are the main value of the country, they need care and special attention. The government is obliged to ensure the implementation of children's rights to upbringing, education and development. The family education of children is the priority form. However, there is a problem of orphanage and social orphanage, children left without parental care. There are various forms of placement for orphans. The family form of the placement, foster families, are priority in the world

Prednisolone Targets Claudins in Mouse Brain Blood Vessels

Endothelial cells in brain capillaries are crucial for the function of the blood–brain barrier (BBB), and members of the tight junction protein family of claudins are regarded to be primarily responsible for barrier properties. Thus, the analysis of bioactive substances that can affect the BBB’s permeability is of great importance and may be useful for the development of new therapeutic strategies for brain pathologies. In our study, we tested the hypothesis that the application of the glucocorticoid prednisolone affects the murine blood–brain barrier in vivo. Isolated brain tissue of control and prednisolone-injected mice was examined by employing immunoblotting and confocal laser scanning immunofluorescence microscopy, and the physiological and behavioral effects were analyzed. The control tissue samples revealed the expression of barrier-forming tight junction proteins claudin-1, -3, and -5 and of the paracellular cation and water-channel-forming protein claudin-2. Prednisolone administration for 7 days at doses of 70 mg/kg caused physiological and behavioral effects and downregulated claudin-1 and -3 and the channel-forming claudin-2 without altering their localization in cerebral blood vessels. Changes in the expression of these claudins might have effects on the ionic and acid–base balance in brain tissue, suggesting the relevance of our findings for therapeutic options in disorders such as cerebral edema and psychiatric failure